1. Field of the Invention
This invention relates to computer circuitry and, more particularly, to methods and apparatus for providing a reference voltage value.
2. History of the Prior Art
In electronic circuitry, it is often necessary to provide a voltage of an exact level for some operation. Moreover, there are situations in which is necessary to provide a voltage of an exact level for some operation at some circuit node which must be charged from some other voltage level.
Where a voltage at a node may vary but must be precisely determined at some instant, there may be a requirement that the node be brought to the appropriate voltage level very rapidly. Typically, the manner in which this is accomplished to a furnish a great deal of current from a power source capable of furnishing high levels of power. There are situations where this is not possible because of power constraints or other circuit constraints. For example, portable computer may lack a source of power sufficient to provide the current necessary to charge a node with substantial inherent capacitance rapidly enough. Even if sufficient power is available, the circuit components may not be capable of providing the current necessary to charge a node at a sufficiently rapid pace. For example, the circuit elements may be constrained in the amount of current they may deliver for other circuit reasons.
It is desirable to be able to provide a voltage of an exact level for operations at circuit nodes at which the voltage must be raised, and it is desirable to provide such a voltage very rapidly.